Plastics have become an integral part of our everyday life, and have been used for a multitude of purposes. They are ordinarily light weight, durable, and easily molded into a variety of forms. However, they have a distinct disadvantage in that plastics are usually not capable of self-decomposition. Thus, a tremendous problem exists with most plastics in their continual accumulation and contribution to the increasing waste problems faced in many countries. The problem of disposal of undecomposible plastics has risen to a point of considerable concern.
Polyethylene is among the most common polymers used in the plastics industry. It has high tensile strength and a high melting point which provides for good blending and easy extrusion into various forms. It is especially useful in making plastic films, which are used in items such as garbage bags. It has the disadvantage of most plastics, however, in not being biodegradable.
Attempts have been made to create plastics which are biodegradable by incorporating starches into polymers. This, however, has contributed its own unique problems. Starch is hydrophilic, while polyethylene is hydrophobic, and so the two are not compatible with one another. Furthermore, when more starch is introduced into a polymer, the resulting plastic film will typically have poor tensile strength.
It would be a considerable advantage to develop a plastic incorporating starch which overcomes the problems of the incompatibility between polyethylene and starch, the loss in tensile strength with the increase in the amount of starch, and still have a product which is easily blended and extruded into the desired form. This invention relates to such an improvement.
Accordingly, it is an object of the invention to provide for a biodegradable plastic having good tensile strength.
Another object of the invention is to provide for a plastic from polyethylene in which the polyethylene is made compatible with starch.
Still another object of the invention is to provide for a plastic which is easily capable of being blended and extruded into a desired form.
Yet another object of the invention is to provide for a plastic which is relatively inexpensive to manufacture.
Still further objects of the invention will become apparent through the following disclosure.